Solve for $x$ and $y$ using substitution. ${-3x+y = 7}$ ${x = -4y+2}$
Answer: Since $x$ has already been solved for, substitute $-4y+2$ for $x$ in the first equation. ${-3}{(-4y+2)}{+ y = 7}$ Simplify and solve for $y$ $12y-6 + y = 7$ $13y-6 = 7$ $13y-6{+6} = 7{+6}$ $13y = 13$ $\dfrac{13y}{{13}} = \dfrac{13}{{13}}$ ${y = 1}$ Now that you know ${y = 1}$ , plug it back into $\thinspace {x = -4y+2}\thinspace$ to find $x$ ${x = -4}{(1)}{ + 2}$ $x = -4 + 2$ ${x = -2}$ You can also plug ${y = 1}$ into $\thinspace {-3x+y = 7}\thinspace$ and get the same answer for $x$ : ${-3x + }{(1)}{= 7}$ ${x = -2}$